Time Line

14th
century – The art of grinding lenses
is developed in Italy and spectacles are made to
improve eyesight.

1590 –
Dutch lens grinders Hans and Zacharias Janssen make
the first microscope by placing two lenses in a
tube.

1667 –
Robert Hooke studies various object with his
microscope and publishes his results in Micrographia.
Among his work were a description of cork and its
ability to float in water.

1675 – Anton van
Leeuwenhoek uses a simple microscope with only one
lens to look at blood, insects and many other
objects. He was first to describe cells and bacteria,
seen through his very small microscopes with, for his
time, extremely good lenses.

18th century –
Several technical innovations make microscopes better
and easier to handle, which leads to microscopy
becoming more and more popular among scientists. An
important discovery is that lenses combining two
types of glass could reduce the chromatic effect,
with its disturbing halos resulting from differences
in refraction of light.

1830 – Joseph Jackson
Lister reduces the problem with spherical aberration
by showing that several weak lenses used together at
certain distances gave good magnification without
blurring the image.